Review: Darkglass Microtubes 900 Head

Since its inception in 2009, Finnish manufacturer Darkglass has earned a level of near-universal respect and admiration among players that belies its short time in the marketplace.
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Since its inception in 2009, Finnish manufacturer Darkglass has earned a level of near-universal respect and admiration among players that belies its short time in the marketplace. While the company’s beautifully designed products and high-end aesthetic are initially seductive, their utilitarian success is what lies behind Darkglass’ meteoric rise. Its initial forays into the bass world revolved around a series of distortion and overdrive pedals under the “Microtubes” banner. Along the way, Darkglass also introduced the innovative Duality Fuzz and Super Symmetry compressor. Each pedal has successfully accomplished its design goal, offering top-notch tube emulation, dynamic and expressive fuzz, and transparent compression. Designer Douglas Castro and his team are good at what they do, and this reputation immediately earned a major buzz with the announcement that Darkglass was developing a bass head. If the stompboxes were as successful as they’ve been, the head should be, too, right?

Right. The Microtubes 900 head is the result of Castro’s long R&D process, and it’s quickly ascended to near the top of the lightweight-amp pile. The reason is the head’s exceptional versatility and gorgeous industrial design. The basic concept behind the amp is the combination of a monstrously powerful 900-watt Class D/SMPS module from ICEpower with an intriguing and innovative preamp that marries a clean channel with a versatile overdrive channel descended from Darkglass’ well-established B3K and Vintage Microtubes stompboxes. Coupled with a flexible and thoughtfully designed EQ section and gig-ready I/O and interface-design, the Microtubes 900 is a do-it-all amp ready to cover a huge swath of gigs.


Out of the box, the most striking thing about the 900 is its gorgeous brushed aluminum chassis. The delicate curves of its corners, the artfully embossed top-panel logo, the high-end hardware—it all adds up to one of the sexiest-looking amps out there. If you’re a fan of the sort of drool-worthy gear adorning the average pro recording studio, you’ll immediately fall for the austerely beautiful Darkglass head. The level of detail is stunning, and it isn’t often I’ve seen so much careful aluminum machining in a bass amp. From the side vents to the countersunk screw holes, the head bears the mark of its design-conscious Scandinavian heritage, with high-quality knobs, switches, and jacks befitting the head’s overall luxury vibe.

The interior construction is no less appealing. Making extensive use of surface-mount construction, the amp basically consists of the ICEpower module, which combines the Class D power amp and switchmode power supply on a single PCB, and an extraordinarily densely packed preamp board. Everything is as orderly as could be, and while the SMD construction makes repairs difficult in the field, the company also made accessing parts like potentiometers and jacks easy.

The Microtubes 900 preamp may seem complex at first blush, but I quickly wrapped my head around it after a few minutes of use. Essentially, without the microtubes switch engaged, the head functions like a straightforward bass amp, with the gain and master controls pairing to facilitate appropriate gain staging. The head’s four bands of EQ include switchable frequencies for the all-important midrange filters, and their centers are well chosen for adding bark, taming boxiness, or bolstering low-end thrust. Depressing the microtubes switch brings in the head’s most killer feature, its highly flexible overdrive circuit. The initial vibe is set via the vmt/b3k switch, with vmt offering slightly dark and warm overdrive compared to the b3k’s more midrangy and aggressive distortion. Once engaged, the Microtubes Engine also offers control over the amount of drive, the output volume of the distortion effect, and—importantly—the ability to blend between the distorted and clean tones.

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All of the above functionality would be irrelevant if the Darkglass didn’t deliver sonically, but that was far from the case. I can say without reservation that the Microtubes 900 has the most flexible and musical-sounding overdrive capability of any solid-state head I’ve come across. That isn’t to say it sounds exactly like an overdriven tube amp, but it’s as close as one could reasonably expect to get with today’s technology. The ability to tame highs with the circuit’s tone knob adds a ton of versatility, and the well-earned Darkglass reputation for responsive and authentic overdrive is in full flush in the head. Whether I wanted to add a touch of gentle midrange color and fur or go for an all-out grind, it was all easily available via the Microtubes Engine. Bonus: The included smart footswitch uses a mono instrument cable to allow for remote switching of the Microtubes Engine as well as muting.

All of the head’s distortion prowess should not take away from its enormously powerful capability as a source for standard, high-headroom clean power. Its 900-watt power amp adds further proof that Class D/SMPS technology is at a point of near parity with more conventional power-amp and power-supply schemes. The head’s clean sound is rich and articulate, with well-textured mids and the kind of buoyant low-frequency responsiveness at high volumes that only comes with big power. I never wanted for more, in spite of pushing the amp to obscene levels in my studio.

The Microtubes 900 is close to the state of the art for bass heads; no longer do we have to compromise weight for power and tone. Its flexibility, durable construction, and thoughtful design make it clear why Darkglass is a major new player in our little corner of the musical instrument industry.



Microtubes 900
Pros Superb and elegant design and aesthetic; robust construction; class-leading overdrive sounds; excellent flexibility; huge power on tap
Cons None
Bottom Line The Class D/SMPS amp game just keeps getting better and better. Darkglass has a true winner on its hands here.


Power rating 900 watts peak @ 4Ω
Preamp Solid-state
Power amp topology Class D
Power supply Switchmode
Outputs One Neutrik Combo; XLR balanced line out; q" preamp out; q" tuner Inputs q" instrument; q" power amp input
Weight 6.4 lbs
Made in Finland


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